‘iOS interview questions’ will be asked for Apple iPhone mobile / iPad tablet / iPod application developers. These interview questions and answers are showcased about the Technical side of an interviews. There are several versions in an iOS like iOS 6, iOS 7 and recent iOS 8 and more. If you are an Apple iOS developer, please go through it..

Many organisation show interest in developing iOS mobile apps for which many companies start hunting for iOS developers. So getting prepared for Apple iOS interview questions and answers for developers is a must. In addition to the above fact people have the fantasy of getting an Apple’s iOS product. Keeping in mind of the above demands we can help you know the importance of iOS and the form of technical questions fired for APP developers during interview are mentioned as follows.

NOTE: It is a Mobile operating system. An iOS stands for ‘iPhone Operating System’!

1) What are the states available in App?

Not running state

Inactive state

Active state

Background state

Suspended state

2) What is the need of @Synthesize?

The generated code can be used without writing any lines of codes. The same gets applicable for getter and setter methods. In order to use them we use two methods namely,

@synthesize

@dynamic

@synthesize will automatically generate the getter and setter methods.

3) How many bytes is it possible to send to Apple push notification Server?

Apple’s push notification server can send 256 Bytes of data at a time.

4) What is the use of NSCoder class in iOS?

NSCoder class is also an abstract class which usually has and represents a stream of data. NSCoder objects are specially used in methods that been already implemented.

Use:

Archiving and unarchiving objects

5) Define CoreData.

CoreData is SQLite Database API(Application Program Interface).In order to store and retrieve the internal state we set CoreData in a class. In other words it can be defined as storing data on disk.

6) Differentiate waterfall and agile methodologies.

Waterfall method

Agile method

In Waterfall method, there will be less interaction with the software development team.

In agile method, there will be a constant interaction with the software development team.

The requirements are well defined in the initial stage itself.

The requirements are added and made during every stage of development

One of the oldest methodology

A modern methodology

7) Explain method swizzling.

The implementation of existing selector is changed.This method is the outcome from the basic idea of method invocation method.

8) Is multitasking a feature in iOS ?

Only the higher versions of iOS gives multitasking feature.

version iOS 4 and above support, where the app remains idle in the background until the current app has been terminated or called.

State transition is changing from one state to another. This is achieved through calling a method and responding to a method.

Example:

applicationWillTerminate is used for termination.

applicationWillEnterForeground for multitasking

10) How do you manage the overview of app’s content on the screen?

View controller object is used to manage the app’s content.It makes views and sub views arranged in the same screen

11) Define Layer Objects.

Layer Objects is used to represent visual content. Layer objects are data objects which are widely used used by views to retrieve their content.In addition to it,for highly sophisticated and complex multimedia videos custom Layer objects can be used.

12) What is a block and its uses?

A block is a set of codes which can be passed to a method. Once it is passed the further actions takes place on the basis of the operations performed in it. Nowadays blocks are more preferred.